Paper machine clothings that are suitable for guiding the paper web through the press section of a paper machine are conventionally embodied as press felts. Such press felts have a support made up of a woven or knitted fabric or a yarn layer, onto which a nonwoven fabric is needle-felted so that the clothing has a felt-like character. Proposals have recently been made to replace the press felts with a paper machine clothing that is assembled from two (or more) extruded webs laid on top of one another, the webs bracing against one another via discrete bracing elements of a wide variety of conformations (cf. EP 0 802 280 A2; WO 01/98580). The bracing elements are also configured during the extrusion process. They are shaped in such a way that they engage into and fit behind one another. They determine the spacing between the two webs. The webs themselves are of porous configuration, so that the liquid pressed out of the paper web in the press can pass through the webs and the paper web is thereby dewatered. Nonwoven layers that are joined to the webs can be applied onto the outer sides of the two webs. In this case the structure made up of the webs and bracing elements forms a support for the nonwoven layers.
Such paper machine clothings have the property that they initially dewater the paper web very well in the front part of the press nip. In the rear part of the press nip, however, a re-wetting of paper web occurs because of the press pressure that continuously or suddenly weakens there, i.e. water flows back into the paper web out of the support and the paper-side nonwoven fabric. The dewatering performance of the paper machine clothing is thereby considerably reduced.
It is the object of the invention to configure a support of the kind cited initially in such a way that re-wetting of the paper web in the rear portion of the press nip is substantially lowered or in fact entirely avoided.